This invention relates to apparatus for lubricating bearings in generators. More specifically, it relates to a lubricating apparatus that supplies a lubricating mist to high speed generator bearings.
Prior lubrication systems for bearings and generators that operate at low rotational speeds, such as 12,000 rpm or less, generally flooded the bearings with oil. These systems adequately lubricated and cooled the bearings in such low speed applications. Further, the frictional forces in the bearings resulting from the oil did not significantly degrade the efficiency of the generator performance at these low speeds.
The recent trend in generator design, particularly in state of the art aircraft generators, is towards higher operational speeds. A requirement for an aircraft generator to rotate at speeds in excess of 20,000 rpm is not uncommon. The advantage of generators which rotate at such higher speeds is the reduction of the generator size and weight for a given load or output which results in more efficient power generation.
At the higher rotational speeds, however, lubrication systems which flood the bearings with oil cause some of the increased generator efficiency resulting from the higher operational speeds to be offset due to losses from bearing friction and from fluid friction. Any improvements in generator performance obtained by increasing the operational speed of the generator should not be offset by increased mechanical losses due to the lubrication system.
A lubrication system for bearings in high speed generators that minimizes mechanical losses, specifically bearing friction and fluid frictional losses, therefore, is needed.